Vertical kiln for continuous grain calcination



Oct. 11, 1966 A. M. COOK ETAL 3,277,585

VERTICAL KILN FOR CONTINUOUS GRAIN CALCINATION Filed Aug. 20, 1963 2 Sheets-Sheet l 9/ mmwwma 4 (34 MC Z 26 flE vo LD 00k FbBE/QT J BLACKMAI? H4 1 BY A TTOENEY Oct. 11, 1966 A. M. COOK ETAL 3,277,585

VERTICAL KILN FOR CONTINUOUS GRAIN CALCINATION Filed Aug. 20, 1963 2 Sheets-Sheet 2 INVEN T0125:

ARA/OLD M 00K 1352 jW A TTOENEY United States Patent 3,277,585 VERTICAL KILN FOR CONTINUOUS GRAIN CALCINATION Arnold M. Cook and Robert J. Blackmar, Holden, Mass.,

assignors to Norton Company, Worcester, Mass a corporation of Massachusetts Filed Aug. 20, 1963, Ser. No. 303,255 2 Claims. (Cl. 34-164) This invention relates to kilns and has for its primary objects to provide a vertical kiln for continuously calcining granular material; to provide a kiln which employs both gravitational and mechanical vibration to effect continuous flow of the material therethrough; to provide a kiln in which rate of flow is controlled by the rate of discharge and vibration; to provide a kiln in which flow of the material is designed to turn the grains over during the course of their flow to expose their surfaces to continuous and uniform heating; to provide a kiln in which heating is effected both by radiation and conduction; to provide a kiln in which contamination of the material being treated is minimized; and to provide a kiln in which the loss of fines is reduced to a minimum.

As herein illustrated, the kiln comprises a refractory structure containing a vertically disposed deviating path consisting of a plurality of continuous courses of reverse slope, the slope of each course may be equal to but is preferably greater than the angle of repose of the material to be treated, means situated adjacent each course adjacent the layer of material for heating the layer during its movement along the course, and means for agitating the structure sufficiently :to cause continuous flow from top to bottom. The deviating path is constituted by vertically spaced shelves situated interiorly of the structure which project alternately from one side wall toward the other and which have downwardly inclined flat upper surfaces which extend from the end wall to end wall, the lower end of each shelf terminating above the upper end of the subjacent shelf and there being a space between the lower end of each shelf and the opposite side wall so that the inclined surfaces and spaces collectively form a continuous deviating passage from top to bottom. The kiln is pivotally supported at its upper end, there is means at its lower end for effecting oscillation about its pivot and a gate for controlling the rate of discharge. The gate is in the form of a rotating cylinder containing pockets adapted to receive the discharge from the lower end of the kiln and there is means for rotating the gate at a predetermined speed. Oscillation of the kiln is effected :by a fluid-operable motor supplied with fluid pressure through a solenoid-operated valve and there is a limit switch situated in a position to be actuated in response to oscillation of the kiln to reverse the position of the valve.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is an elevation of the supporting frame showing the kiln in vertical section, with a platform or floor above the frame from which material may be shoveled through an opening into the top of the hopper at the top of the kiln;

FIG. 2 is an enlarged elevation taken at right angles to FIG. 1, with portions shown in section; and

FIG. 3 is a detail view partly in section of a single brick such as is used in a stacked relationship with identical bricks to form the refractory passage of the present kiln.

Referring to the drawings, the apparatus comprises, in general, a supporting frame 10, a vertically disposed kiln 12 suspended at its upper end from the frame, a discharge gate 14 at the lower end of the kiln for removing material therefrom at a controlled rate, and a conveyor 16 for receiving the discharge and conducting it to a place for storage or use.

The frame 10 has a rectangular top part comprised of I-beams 18 mitered at their ends and welded to each other. A pair of channel beams 20-20 are welded crosswise of the top part back-to-back 'with their webs in spaced parallel relation. The top part is supported at its four corners by four legs 22 which extend downwardly therefrom in diverging relation to each other. The legs 22 are secured intermediate their upper and lower ends by horizontal cross-braces 24 and have foot plates 26 welded to their lower ends. A horizontally disposed plate 28, secured to the legs below the cross-braces 24, provides a support for certain parts of the apparatus as will be related hereinafter and contains a centrally located, substantially rectangular opening 28a.

The kiln 12 is supported in a vertical position within the frame 10 and to this end a hanger 30 is pivotally supported by a bolt 32 between the beams 20-20, the lower end of which is pivotally connected by a pivot bolt 34 between channel beams 36-36 at the top of the kiln.

The kiln is of double-wall construction, having inner and outer walls 38 and 40 with insulation 42 therebetween, and is of rectangular cross-section, the side walls 39 being somewhat wider than the end walls 41. At the lower end of the kiln there is a bottom plate 44 which is joined at its edges to the lower ends of the side and end walls. The bottom plate has a downwardly projecting portion or chamber 46 of rectangular crosssection extending through the opening 28a in the support 28 and has at its bottom a rectangular opening 48. The inner walls 38 of the double-wall construction (FIG. 1) terminate short of the bottom plate 44 and a plurality of refractory bricks 50 are stacked in the lower part of the kiln between the lower ends of the inner walls and the bottom plate and within the chamber 46. The bricks are stacked so as to provide a narrow, vertically disposed discharge passage 52 which extends from end wall to end Wall and a chamber 54 at the upper end also extending from end-to-end, one side of which has an inclined supporting surface 56. The lower end of the discharge passage 52 is situated within the opening 48 at the bottom of the chamber 46.

A plurality of layers of blocks 58 are stacked in spaced relation against the inner side of the wall 38 on the upper layer of bricks 50, commencing at the lower ends of the inner walls 38. The blocks 58 are of rectangular section, have vertical inner side surfaces or portion 62, circular holes 64 at their mid-lengths, the axes of which are perpendicular to their inner side surfaces, and there are plug blocks 66 made of insulation material inserted in the holes. The blocks 58 each have an integrally formed shelf 70 extending from their inner side toward the opposite vertical inner side surfaces 62 thereof. The shelves 70 have upper and lower downwardly inclined surfaces 72 and 74 and vertical end surfaces 76 spaced from and parallel to the said inner side surfaces 62. The lowermost of the blocks 58 is supported on the upper layer of brick means 50 with its vertical inner side surface 62 coinciding with the upper edge of the inclined surface 56 and the lowermost block 58 is supported on the upper layer of bricks 50 so that the upper inclined surface 72 slopes in the direction opposite to the surface 56 and so that its lower end surface 76 terminates above the upper end of the slope 56. The successive layers superposed upon the first layer are arranged so that the blocks 58 are reversed in each layer. Thus, the oppositely inclined upper surfaces 72 and the openings 78 formed between the lower ends 76 of the shelves and the inner vertical surfaces 62 collectively provide a deviating path from top to bottom for conducting the material to be treated through the kiln in a relatively thin layer, the thickness of the layer being controlled by the width of the openings 78.

In the preferred construction, the slope of the upper inclined surfaces. 72 is designed to be greater than the natural angle of repose of the particular product that is being treated.

A plurality of heating elements in the form of resistance rods 80 are mounted between the shelves with their axes parallel thereto and with their ends extending through the end walls 41, there being two such resistance rods situated above the upper inclined surface 72 of each shelf and one situated in the angular space beneath the lower inclined surface 74 of each shelf. This arrangement provides for heating the granular material resting on the shelf from below by conductance and from above by radiation. The resistance rods are connected by suitable Wiring to a source of power.

The side walls 39 contain openings 39a through which the plugs 66 may be removed to afford access to the interior of the kiln. Each plug contains an inclined opening 66a within which may be inserted a thermocouple for indicating and providing for control of the heating.

The upper end of the kiln (FIG. 1) is closed by a top plate 82 in which there are spaced holes 84-84 adjacent the upper end of the upper inclined surface 72 of the topmost layer of blocks. Funnel tubes 86-86 are inserted into the openings 84-84 and a hopper 88 is mounted to straddle the beams 20-20 and has spaced legs 90-90 extending downwardly into the upper ends of the tubes 86-86 for supplying the granular material to be treated to the upper end of the kiln. A floor 89 above the upper end of the support contains a hole 91 providing for loading the hopper 88.

In order to assist the gravitational flow and effect continuous flow of the granular material downwardly through the kiln, oscillation or vibration of the kiln is provided by means of a link 92 fixed at one end to the chamber or portion 46 and pivotally connected at its other end by a pin 94 to a piston rod 96 protruding from a double acting piston motor having a cylinder 98. The cylinder 98 is p-ivotally mounted on a pin 100 supported by a bracket 102 which is fastened to the underside of the support 28. A solenoid-operated valve V is mounted on the support 28 and is supplied through a conductor 106 with pressure fluid. The valve V is connected to the opposite ends of the cylinder 98 by conductors 108 and 110 and a spool 112 situated in the valve is shiftable by solenoids S1 and S2 to supply pressure fluid to one or the other of the ends of the cylinder 98. A threaded rod 114 is fastened to the lower part of the kiln on which are adjustably mounted a pair of plates 116-116 which are movable with the kiln relative to an actuator 118 of a limit switch LS mounted on the support 28, so as to reverse the current to the solenoid-operated valve to excite first one solenoid and then the other, and thus to shift the valve. The wiring for the solenoids S1, S2 and switch LS is shown at 0'. By adjusting the position of the plates 116-116 the rate and length of oscillation or vibration may be adjusted.

The gate 14 for effecting discharge comprises a cylinder 120 (FIG. 2) containing on its peripheral surface, axially disposed, parallel grooves 122 and the gate device is supported for rotation about the axis of a horizontally disposed shaft 124 with the uppermost groove 122 vertically subjacent the lower end of the discharge opening 52. The ends of the shaft 124 are supported in journals 126 secured to the upper ends of posts 128. Rotation of the gate 14 is effected by a sprocket 130 secured to one end of the shaft 124, a chain 132 entrained at one end about the sprocket 130 and at its other end about a sprocket 134 driven by a gear reduced R which, in turn, is driven by a motor M. A motor control MC of conventional kind may be employed for controlling the rate of rotation and/or the length of operation of the motor. The kiln may be oscillated when in use at a rate of about 60 to 100 oscillations per minute but a faster or slower rate may be more appropriate depending upon the size and kind of material being processed.

A conveyor belt 136 is supported below the discharge gate 14 with its upper run in a substantially horizontal plane for receiving the material removed by the gate from the lower end of the kiln and transporting it to a place of storage or use.

The particular advantages of the apparatus reside in the provision of continuous controlled flow of the granular material in a relatively thin layer in cascading fashion, so that the individual grains are turned over and over for complete exposure to heating throughout their travel from top to bottom and of heating both by conductance and radiation from both sides and of maintaining the flow and the heating within a confined space free of contamination and of moving air currents which prevents loss of fines. It is to be understood however that where the material to be treated would not be adversely affected by products of combustion and of such coarseness as not to be readily entrained by turbulent gases of combustion, that the apparatus may be provided with means for conducting hot gases of combustion along with the material to be treated through the devious passage between the successive layers of blocks for effecting calcination.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

- I claim:

1. A kiln comprising a plurality of layers of refractory blocks constituting a stack, each layer being formed of a block arranged in parallel relation with another one of the blocks, each block having a projection extending therefrom toward an opposite wall thereof, said projection having upper and lower inclined surfaces, the inclined surfaces in successive layers being inclined in opposite directions and enclosing a space, the opposite wall of each layer having a substantially vertical surface opposite its respective upper inclined surface, each opposite wall containing an opening perpendicular to the vertical surface and a closure filling said opening, resistance rods disposed in the spaces between layers with their axes substantially parallel to the inclined surfaces, there being at least one such rod intermediate the top and bottom of a layer above the upper inclined surface and at least one such rod intermediate the top and bottom of the layer beneath the lower inclined surface, means supporting the stack for pivotal movement about a horizontal axis substantially parallel to the inclined surfaces, means at the bottom of the stack for effecting oscillation about said axis, and a gate at the bottom of the stack for removing material from the bottom at a controlled rate.

2. Apparatus according to claim 1 wherein the means for effecting oscillation about said axis comprises a link connected to the lower end of the kiln a fluid-operated motor connected to the link, valve means for supplying fluid to the motor, and a limit switch operable, by oscillation of the kiln, to reverse the position of the valve means.

References Cited by the Examiner UNITED STATES PATENTS 685,336 10/1901 Leroy et a1. -Q 34-171 1,210,852 1/1917 Schefczik 263-25 1,554,780 9/1925 Berrigan et a1 34-171 X 1,611,098 12/1926 Borner 34-171 X 1,626,805 5/1927 Forrest 34-1'71 X 2,020,504 11/1935 Hant-la 34-171 X 2,187,799 1/1940 Baughman 34-171 2,362,718 11/1944 Pidgeon 13-22 X 2,983,051 5/1961 Zimmermann et al. 34-171 X FREDERICK L. MATTESON, JR., Primary Examiner.

WILLIAM F. ODEA, Examiner.

D. A. TAMBURRO, Assistant Examiner. 

1. A KILN COMPRISING A PLURALITY OF LAYERS OF REFRACTORY BLOCKS CONSTITUTING A STACK, EACH LAYER BEING FORMED OF A BLOCK ARRANGED IN PARALLEL RELATION WITH ANOTHER ONE OF THE BLOCKS, EACH BLOCK HAVING A PROJECTION EXTENDING THEREFROM TOWARD AN OPPOSITE WALL THEREOF, SAID PROJECTION HAVING UPPER AND LOWER INCLINED SURFACES, THE INCLINED SURFACES IN SUCCESSIVE LAYERS BEING INCLINED IN OPPOSITE DIRECTIONS AND ENCLOSING A SPACE, THE OPPOSITE WALL OF EACH LAYER HAVING A SUBSTANITALLY VERTICAL SURFACE OPPOSITE ITS RESPECTIVE UPPER INCLINED SURFACE, EACH OPPOSITE WALL CONTAINING AN OPENING PERPENDICULAR TO THE VERTICAL SURFACE AND A CLOSURE FILLING SAID OPENING, RESISTANCE RODS DISPOSED IN THE SPACES BETWEEN LAYERS WITH THEIR AXES SUBSTANTIALLY PARALLEL TO THE INCLINED SURFACES, THERE BEING AT LEAST ONE SUCH ROD INTERMEDIATE THE TOP AND BOTTOM OF A LAYER ABOVE THE UPPER INCLINED SURFACE AND AT LEAST ONE SUCH ROD INTERMEDIATE THE TOP AND BOTTOM OF THE LAYER BENEATH THE LOWER INCLINED SURFACE, MEANS SUPPORTING THE STACK FOR PIVOTAL MOVEMENT ABOUT A HORIZONTAL AXIS SUBSTANTIALLY PARALLEL TO THE INCLINED SURFACES, MEANS AT THE BOTTOM OF THE STACK FOR EFFECTING OSCILLATION ABOUT SAID AXIS, AND A GATE AT THE BOTTOM OF THE STACK FOR REMOVING MATERIAL FROM THE BOTTOM AT A CONTROLLED RATE. 